Process of reacting cellulose textile with beta-propiolactone or beta-isovalerolactone



PROCESS or REACTING CELLULOSE TEXTILE WITH BETA-PROPIOLACTONE on BETA-ISO- VALEROLACTONE Robert M. Reinhardt, George C. Dan], and John D. Reid, New Orleans, La., assignors to the United States of America as represented by, the Secretary of Agriculture No Drawing. Application November 20, 1953-,

Serial No. 393,523

3 Claims. (Cl. 8-116).

(Granted under Title 35, 0.5. Code 1952 sec. 266) A nonexclusive, irrevocable, royalty-free license in the invention herein described, for all governmental purposes, throughout the world, with the power to grant sublicenses for such purposes, is hereby. granted to th Government of the United States of America.

This invention relates to beta-propiolactone reacted cellulose fibers and provides an improved process of producing such fibers.

This application is a continuation in part of our co pending application, Serial No. 299,772, filed July 18, 1952, which relates to beta-propiolactone reacted cellulose fibers produced by reacting cellulose fibers with betapropiolactone at from about 50 to 155 C. until fibers are produced containing from about 0.5 to 26%, based on the weight of the original fibers, of beta-propiolactone reaction products combined with the cellulose. The betapropiolactone combines with the cellulose within the Walls of the fibers and materially alters the properties of fibers by imparting certain new properties and enhancing certain desirable properties. For example, the reaction materially increases the effective diameter of the fibers and gives them a wool-like feel, and resilience, in addition to a greater heat resistance, dye resistance, acid degradation resistance, wrinkle resistance, and the like, without appreciably reducing their tensile strength.

Beta-propiolactone is a liquid which tends to polymerize at elevated temperatures. In accordance with our copending application, its reaction with cellulose fibers is accomplished by contacting the fibers with hot solutions of beta-propiolactone in organic liquids, or with the vapors arising from such solutions, and, in order to free the fibers of adhering but uncombined substances, washing the so treated fibers with a liquid organic solvent such as acetone. Such a process requires specializedequipment designed to handleinfiammable vapors. l

A primary object of the present invention is to provide an efiicient, fast, and commercially feasible process of producing the same beta-propiolactone reacted cellulose fibers, that is, fibers containing from about 0.5 to 26%, based on the weight of the original fibers, of betapropiolactone reaction products combined With the cellulose, by a process which can be conducted in the usual textile impregnating equipment such as extractors, padders,

quetches and the like.

in general, according tothe present invention, cellulose fibers are impregnated with an aqueous 5m 50 percent alkali metal hydroxide solution, preferably aqueous sodium hydroxide solution, and the aqueous alkali wet fibers are reacted with beta-propiolactone, preferably in a concentration of at least about 5%, that is, ranging from at least about 5% in solution in water or in an inert solvent to the pure form (100%), at a temperature fromabout C. to 30 C., until fibers are produced containing from about 0.5 to 26%, based on the weight of the original fibers, of beta-propiolactone reaction products combined with the cellulose. Thereafter, the uncombined substances 0 fibers.

2,731,323 Patented Jan. 17,1956

The use of beta-isovalerolactone in place of the beta-propiolactone yields analogous products.

The reaction between the beta-propiolactone and the alkali-wet fibers is exothermic. At room temperature the rate of reaction depends primarily upon the type and concentration of the alkali metal hydroxide and the concentration of the beta-propiolactone.

Sodium and potassium hydroxides are preferred alkali metal hydroxides for employment in the present process. Sodium hydroxide is particularly suitable. Aqueous alkali I h metal hydroxide concentrations of from about to 30% are preferred, and concentrations of from about to are particularly suitable.

The cellulose fibers can be impregnated with aqueous alkali metal hydroxide using the usual textile impregnation procedures and apparatus. Preferably, the impregnated fibers are freed ofexcess liquid, i. e., the amount not sorbed by the fibers, by mechanical means such as rolls, centrifuges, and the like. The impregnation is preferably conducted at about room temperature and contact time between the fibers and the aqueous alkali-metal hydroxide is preferably relatively short, to reduce the amount of alkali induced degradation. The impregnation is preferably conducted in padders and quetches having rolls set to a relatively tight nip.

The cellulose fibers wet with aqueous alkali can be immersed in pure beta-propiolactone or beta-propiolactone tion of beta-propiolactone mechanically freed of excess are removed, as by water washing, from the resulting liquid and allowed to remain at about room temperature, or below, with or without drying, during the reaction.

Suitable solvents for the beta-propiolactone include water and inert liquid alcohols suchas tert-butyl alcohol; ketones such as acetone; ethers such as dioxane; hydrocarbons such as hexane, benzene, toluene, or xylene, or the like. Although beta-propioiactone will react with water under certain conditions, its rate of reaction with water is such that water solutions of betapropiolactone can be reacted with alkali-impregnated cellulose in accord ance with this invention. Liquid aromatic hydrocarbons such as benzene, toluene, xylene, and the like are preferred inert solvents.

Apparently, the reaction between beta-propiolactone and alkali proceeds more rapidly as heat is produced, therefore it is advantageous to cool the beta-propiolactone solutions during'the reaction with alkali-impregnated cellulose. This minimizes the amount of alkali-beta-propiolactone by-products.

The reaction of the cellulose fibers with beta-propiolactone can be terminated by water washing the fibers free of uncornbined reactants, or by neutralizing any alkali remaining in contact with the fibers with dilute aqueous acid. Substantially, any aqueous acid and any fibercontacting procedures or equipment can be used. The neutralization of the alkali with an aqueous solution of a Water soluble organic acid, such as acetic acid, is particularly suitable.

The beta-propiolactone reacted fibers are washed free of uncombined reactants, with hot water. The Washing substantially completely removes adhering beta-propiolactone-alkali hydroxide products which are not chemically attached to the cellulose and leaves the fibers with a soft, wool like hand and feel.

Cellulose fibers which can be used include cotton fibers such as lint, linters, and the like, and regenerated cellulose fibers such as viscose rayon fibers, before or after bleaching, mercerization, and the like treatments.

The cellulose fibers can be reacted in the form of free fibers, sliver, yarn, or fabric. The use of yarns, threads or cloth is preferred.

. tion at moderately elevated temperatures.

The beta-propiolactone rcactedfibers are useful for substantially any of the wide variety of uses known for' cellulose fibers. Beta-propiolactone reacted fibers are particularly useful wherever woo1-like properties and properties such as a dye resistance, a heat resistance, an acid induced degradation resistance and a wrinkle resistance markedly greater than those-of cellulose textile fibers is important. In addition, the beta-propiolactone reacted fibers can readily be produced in the form of unsaturated compositions which undergo the. reactions typical of or ganic compounds containing olefinic groups. These unsaturated fibers constitute valuable intermediates from which to prepare numerous difierent derivatives of cellulose in the form of textile fibers.

Beta-propiolactone reacted cellulose fibers are produced in the form of appreciably unsaturated fibers by dehydra- A preferred process of producing them comprises immersing such fibers in a water immiscible inert organic liquid, refluxing the liquid, and isolating water from the liquid returning from the condenser. The water immiscible solvents for beta-propiolactone are preferred liquids for such employ ment. The dehydration is preferably conducted at from about 50 C. to about 150 C. The dehydration can be conducted by a wide variety .of conventional procedures for dehydrating solid compositions at moderately elevated temperatures. Such unsaturated fibers are composed essentially of the dehydration products of cellulose-betapropiolactone reaction products.

Other beta-lactones of alkanoic acids may be employed in carrying out the process of this invention; for example, beta-isovalerolactone yields analogous products.

The following examples are illustrative of the invention (BPL refers to beta-propiolac'tone).

Example 1 A 20 yd. skein of purified .(by ethanolamine extraction) 12/5 cotton sewing thread (i. e., a thread composed of plies of a yarn of which 12 x 840 yards weighs 1 pound) was placed in a flask with 70 ml. of pure beta-propiolactone and allowed to stand at room temperature for 18 hours. It was removed and extracted with acetone in a Soxhlet apparatus to remove unbound polymer and unreacted reagent. Weight gain was 2.7%.

This example is given to show the negligible amount of reaction which occurs when cellulose fibers which are not impregnated with aqueous alkali are maintained in contact with beta-propiolactone at about room temperature.

Example 2 Twenty yard skeins of purified cotton 1.2/5 sewing thread were soaked in various concentrations (540%) of sodium hydroxide solution, freed of excess solution by centrifugation, soaked in beta-propiolactone, drained free g 7 Examples 7 i A 20-yard skein of purified cotton sewing thread which had been treated with sodium hydroxide and beta-propiolactone, by a procedure. equivalent to that described in Example 2, was extracted with water in, a heat-jacketed Soxhlet apparatus. Weight gain of the thread after extraction was 18.8%. The skein was then extracted with acetone in a Soxhlet apparatus but lost no additional weight.

This example is given to show that the unbound polymeric material formed in the sodium hydroxide-betapropiolactone treatment is completely extractable with hot water.

Example 4 Twenty-yard skeins of purified cotton 12/5 sewing thread-were soaked in various concentrations of sodium hydroxide solution (545%), centrifuged free of excess solution, weighed for wet pickup and placed in beakers containing 25 ml. of beta-propiolactone cooled to -10 C. The beakers were immersed in an ice-salt bath to maintain the lowered temperature. Skeins treated with 520% sodium hydroxide solutions remained at the lowcred temperature but the 25% sodium hydroxide-treated sample boiled over while in the ice-salt bath. After the reaction had subsided, the skeins were removed, washed with water, neutralized, washed again and then extracted with hot water in a Soxhlet apparatus. Results of the treatments are shown in the table below.

Wet pickup. Wei

ght Cone. of NaOH s0ln., percent 2 gain, 1 ig percent Deleon Controlnn 0. 0266 110. G 13. 5 0. 0328 112. 2 21. 5 O. 0354 163. 3 43. 2 0. 0375 155. 8 35. 7 0. 0399 169. 3 18. 9 0. 0369 Example 5 Twenty-yard skeins of purified cotton sewing thread were soaked in 15% sodium hydroxide solution, centrifuged to about 160% wet pickup, then soaked in ml. portions of solutions of beta-propiolactone in water for 1 hour. The higher concentration solutions warmed up but did not reach the boiling point. After the reaction, the thread was washed with water, and extracted with hot water in a Soxhlet apparatus to remove unbound re actants. Results are shown in the table below:

,. of excess, and allowed to stand for. one hour on watch 50 glasses. After a short induction period, heat developed Wet pickup Weight and then the samples cooled to room temperature. After BPL -i Percent of NaOH, gain, standing, the samples were washed in distilled water, neupercent percent tralized with acetic acid, washed again with water and 5 166 5 0 7 extracted exhaustively in a Soxhlet apparatus'with ho 10411 819 acetone. Results are shown below: I fig"? 155:6 1917 148.0 21.1 wot p p 140. 7 22. 8 Cone. of NaOH 50111., percent 313011 remit Thiqknessr Dem; percent in.

Example 6 g ff ff iii g, 813 93 Skeins of purified 12/5 sewing thread were soaked 9.3 0 0328 in 15% sodium hydroxide solution, centrifuged to about 18011 3 819.2%? wet pickup and then soaked in 50 ml. portions of g gaqueous solutions of beta-propiolactone of various conj 1 j 0360 centrations. in an icexhath for one hour. The temperature 7 3 0347 was .mnintflinediatebmrt 5 '-C. After standing, the skeins ere Washed with water and then exhaustively aransas extracted in a heat-jacketed Soxhlet apparatus with water. Results are shown in the table below; L

wet ickup OIIJAOH,

percent BPL cone; percent 1 This concentration was temperature used.

1 Example 7 Twenty-yard skeins of purified 12/5 sewing thread were soaked in 15% NaOH and centrifuged to approximately 160% wet pickup of alkali. The skeins were then soaked in beta-propiolactone, drained of excess and allowed to stand on a watch glass for various times to 120 minutes). water and then extracted with hot water to remove unbound reactants. Results are shown in the table below:

Wet pickup of NaOH, solution percent Time of reaction, Minutes Skein dipped in beta-propiolactone and washed immediately.

Example 8 Twenty-yard skeins of purified cotton 12/5 sewing thread were soaked in 15% sodium hydroxide solution, centrifuged of excess solution and soaked in 50 ml. of various concentrations (80%) of beta-propiolactone in xylene for 1 hour. Samples treated with 60 and 80% beta-propiolactone became so hot that they boiled over. The skeins were washed, neutralized and extracted with hot water in a Soxhlet apparatus. Results are shown in the table below: 1

Weight gain, per- Cone. of NaOH solution, percent cont Example 9 After standing, the samples were washed. with apparatus. Results of the treatments are shown below:

Pickup 0! 3 We ght Cone. oi BPL solution, percent gf g m, Thit l r ness, a percent Example 10 A skein of purified cotton 12/5 sewing thread was soaked in 15% sodium hydroxide solution, centrifuged to 169.8% wet pickup and then soaked in a 35 solution of beta-propiolactone in acetone, drained of excess and placed on a watch glass for 1 hour. The treated skein was then washed with water, neutralized with acetic acid, washed again and extracted with water in a Soxhlet apparatus. The Weight gain was 18.5%.

Example 11 A similar treatment was given to another skein of cotton sewing thread except that a 35% solution of betapropiolactone in dioxane was used. Weight gain in this case was 17.8%.

Example 12 Twenty-yard skeins of raw 12/5 cotton sewing thread was extracted with acetone to remove waxes, then soaked in solutions of potassium hydroxide of various concentrations and centrifuged to remove excess. The skeins were soaked in beta-propiolactone, drained of excess and allowed to stand for 1 hour. The reactions were exothermic; inthe case of the skeins treated with 40 and 50% potassium hydroxide, the reactions were of an explosive character. After standing for 1 hour, the skeins were washed with water, the alkali neutralized with dilute acetic acid, washed again with water and extracted with hot water in a Soxhlet apparatus to remove unbound byproducts. Results of this experiment are shown in the table below:

Pickup of Example 13 Samples of purified low viscosity cotton linters weighing 1.62 g. each were impregnated with various concentrations of sodium hydroxide (10-50%), padded to re- Pickup oi c Wei ht Y Cone. of NaOH soln., percent i g g hyl cou- 5 percent tout cont 106.8 28. 7 7. 04 214. 8 35. 5 7, 97 230. 9 61. e 10. 31 243. 8 51.1 a 35 250. o 44. s 47 I Determined by titration.

, :1 W Example 14 Pieces of 48 x 48 scoured cotton sheeting were padded with 5, 10, and 15% sodium hydroxide solutions, respectively, and soaked in beta-propio'lactone for '1 hour at room temperature. The first two samples became warm, while the cloth treated with the 15% alkali became very hot. After reaction, the cloth was extracted with ethyl alcohol and then with hot water in a Soxhlet apparatus.

Pieces of 48 x 48 scoured cotton sheeting were soaked in 5, 10, and 15% sodium hydroxide solutions, respectively, and centrifuged to remove excess alkali. The samples were then dipped in bctapropiolactone and given a light pad to remove excess. The cloth was collected on a roll and allowed to stand for 1 hour. There was some heat given off during the reaction. After standing, the cloth was washed in water, neutralized with dilute acetic acid, washed again with Water and extracted with hot water to remove unbound reactants. Results are shown below:

' Pickuu of weiwht Cone. of NaOH solution, percent gfli l l, Tmqkness $0111., perin.

com; percent 8 'Example 16 A 20-yard skein of extracted cotton sewing thread was soaked in sodium hydroxide, centrifuged to 190.6% wet pickup and placed in 25 ml. of a solution of beta-isovalerolaetone in tert.-butyl alcohol and allowed to stand for 1 hour. It was washed with water, neutralized with acetic acid and rewashed. It was then extracted with hot acetone. Weight gain was 6.1% Weclaim:

l. A process comprising impregnating cellulose textile fibers with an aqueous 5 to per cent alkali metal hydroxide solution, reacting the aqueous alkali wet fibers with a lactone selected from the group consisting of beta-propiolactone and beta-isovalerolactone at a temperature from about 0 C. to 30 C. until fibers are produced containing from about 0.5 to 26%, based on the weight of the original fibers; of the lactone reaction products combined with the cellulose, and removing uncombined substances from the. resulting fibers.

2. A process comprising. impregnating cellulose textile fibers with an aqueous 5 to 50 per cent alkali metal hydroxide solution, reacting the aqueous alkali wet fibers with an aqueous solution of a lactone. selected from the group consisting of beta-propiolactone and beta-isovalerolactone in a concentration of at least about 5%, at a temperature from about 0 C. to 30 C., until fibers are produced containing from about 0.5 to 26%, based on the weight of the original fibers, of the lactone reaction products combined with the cellulose, and removing uncombined substances from the resulting fibers.

3. The process of claim Z'WhCI'Gil'l the lactone is betapropiolactone.

No references cited. 

1. A PROCESS COMPRISING IMPREGNATING CELLULOSE TEXTILE FIBERS WITH AN AQUEOUS 5 TO 50 PER CENT ALKALI METAL HYDROXIDE SOLUTION, REACTING THE AQUEOUS ALKALI WET FIBERS WITH A LACTONE SELECTED FROM THE GROUP CONSISTING OF BETA-PROPIOLACTONE AND BETA-ISOVALEROLACTONE AT A TEMPERATURE FROM ABOUT 0* C. TO 30* C. UNTIL FIBERS ARE PRODUCED CONTAINING FROM ABOUT 0.5 TO 26%, BASED ON THE WEIGHT OF THE ORIGINAL FIBERS, OF THE LACTONE REACTION PRODUCTS COMBINED WITH THE CELLULOSE, AND REMOVING UNCOMBINED SUBSTANCES FROM THE RESULTING FIBERS. 